1. Field of the Invention
This invention relates generally to high pressure reciprocating pumps of the type used in high pressure waterjet applications, and more particularly to an improved high pressure reciprocating pump and manifold, stuffing box, plunger packing, and valve components therefor.
2. Description of the Prior Art
High pressure reciprocating pumps, such as those utilized in high pressure waterjet cleaning and cutting and hydrostatic testing, are often required to produce fluid pressures up to 35,000 psi. Pumps in this type of service commonly require power inputs in excess of 100 horsepower. Because of inherent high cyclic internal pressures and damage caused by impurities in the fluid being pumped, these types of pumps are prone to fatigue failures and require considerable maintenance.
Various prior art pumps intended for high pressure applications are subject to breakage or failure due to excessively high stress concentration at certain points in the pump structure, leakage from the high pressure side of the pump system either to atmosphere or the low pressure side of the system, entrapment of air or gases during operation of the pump, with consequent loss of efficiency and/or hammering, etc.
More specifically, one of the problems encountered with many high pressure pumps arose because of the utilization of pump structure cavities or bores having their axes arranged in relatively angled relationship, for instance at right angles to each other. Thus, in certain high pressure pumps a bore for the pump plunger was arranged at right angles to the bore for certain of the valve structures, resulting in a corner of metal between the right angle bores. This results in an excessive stress concentration at the corner, which causes cracks and failure in the metal, particularly where very high pressures are handled.
The following U.S. Patents disclose pump structures having valve bores arranged at right angles to each other and/or to the pump plunger bore: 4,227,229; 4,432,386; and 3,373,695.
Attempts to reduce the stress concentration have included making the valve housing of hard alloy material which are expensive and difficult to machine, or rounding or chamfering of the corners where stress concentration occurs. This remedy becomes less desirable at very high pressures because of the progressively smaller diameter bores used for the high pressures, resulting in increased difficulty to access to the corners for the necessary machining to round or chamfer the corners.
Other attempts at reducing the stress concentration include arranging the valve mechanisms coaxially of and mounting them to move in directions generally parallel to the motion of the pump plunger in its operating cylinder. Many pumps of this type have the disadvantage of poor suction conditions, low volumetric efficiency, and exposure of the seals to cyclic pressures.
The following U.S. Patents disclose pump structures having valve bores arranged coaxially with the pump plunger bore: 4,551,077; 3,372,648; 3,114,326; 3,508,849; 3,709,638; 4,239,463; and 3,370,545.
The present invention is distinguished over the prior art in general, and these patents in particular by a high pressure reciprocating pump having a mounting flange plate secured to the plunger end of the pump drive housing and a suction and discharge manifold is hingedly connected to the mounting flange. A stuffing box in bores in the mounting flange has a central bore which slidably receives one end of the plunger and forms a plunger pressure chamber coaxial with the plunger. A tapered packing assembly in the stuffing box surrounds the plunger in reciprocal sealing relation. A suction and discharge valve cartridge is one or more valve cavities in the manifold block is coaxial with the plunger.
The hinged connection clamps the stuffing box in the mounting flange and allows the manifold pivot for clear access to both the stuffing box and the valve cartridges permitting either to be removed independently of the other for easy field maintenance. The valve cartridge comprises a common seat member having a suction valve and a discharge valve movably mounted coaxial with the plunger and positioned concentric and radially spaced on the seat. When assembled, the valve cartridge is mechanically biased in the cavity by the stuffing box. The seat member has seals positioned to seal the cavity and the stuffing box around the pressure chamber. The seals are sized and positioned such that the valve cartridge is hydrostatically biased and urged toward the stuffing box by the fluid forces acting thereon during operation of the pump plunger.